This invention relates generally to a method of developing porosity in an air impervious film or laminate. The invention further relates to a cushion article and a process for fabricating the article with a cover having increased air flow capabilities.
One area in which the invention has particular applicability is in the art of fabricating cushion articles. Traditional methods of making upholstered seat cushions, for instance, have involved (1) cutting the cover material according to an appropriate pattern; (2) sewing the cut material; and (3) stuffing the cushion. High labor costs result since, in many instances, the cutting and sewing operations are extensive and most often are performed by hand.
To reduce the costs of manufacturing seat cushions, a molding process was devised for manufacturing seat cushions comprising a foam portion having an integral vinyl cover. The vinyl cover first is heated and then drawn into a cold mold by means of a vacuum between the vinyl and the mold. As the vinyl cools, it assumes the contours of the mold. Foam then is poured into the mold to form the foam portion of the seat cushion. This process significantly reduces manufacturing costs and results in a superior seat.
However, cloth has many advantages over vinyl. Specifically, cloth is water vapor permeable. Perspiration that normally collects behind a person sitting in a vinyl seat can evaporate through cloth so that cloth covered cushions feel cooler during warm weather and warmer during cold weather. Furthermore, the feel of cloth is much more luxurious and elegant.
In recognition of these advantages, a novel molding process was devised for manufacturing seat cushions comprising a foam portion having an integral cover including an outer cloth layer. Such a process is disclosed in U.S. Pat. Nos. 4,247,348 and 4,264,386. In that process the stitch of the fabric layer in set in the mold. This may be accomplished by employing a mold heated to at least the fabric temperature when the cloth is drawn into the mold. The fabric layer is thereby heated and then allowed to cool. By this process the fabric stitch is set and the cloth is formed to the precise contours of the mold. Foam then is poured into the mold after the cooling step to form an integral seat cushion with a fabric cover. The fabric normally is bonded or laminated to a vinyl film to permit the cover to be vacuum drawn into the mold.
All of the above innovations in the art have resulted in labor savings and improved products. Yet, one of the problems remaining with making seat cushions or other cushion articles by the above process is insufficient air flow through the covering. As stated above, cloth has an advantage over vinyl in that the cloth is water vapor permeable. However, when the cloth is laminated to a vinyl layer to permit vacuum drawing of the laminated cover into the mold, the cloth loses much of its air flow capabilities. In certain fields, such as the automotive industry, this air flow capability is called "breathability".
A common method of providing breathability in covered cushion articles is illustrated in U.S. Pat. No. 3,258,511 to McGregor, dated June 28, 1966. In that patent, a cushion article has a cloth cover laminated to an air impervious film. After the cushion article is fabricated, the cover is punctured by a roller having needle-like projections. One of the problems in puncturing a vinyl backed cloth cover is that the projections have a tendency to break the yarn of the fabric, thereby diminishing the durability and appearance of the upholstered cushion.
The present invention contemplates solving these problems by a novel method of developing porosity in an otherwise air impervious film or laminate, thereby providing increased air flow capabilities in such items as cushion articles, particularly articles which include a cover comprising a portion thereof fabricated of air impervious film.